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NEW TIES WP2 Agent and learning mechanisms
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Decision making and learning Agents have a controller (decision tree, DQT) Input: situation (as perceived = seen/heard/interpr’d Output: action Decision making = using DQT Learning = modifying DQT Decisions also depend on inheritable “attitude genes” (learned through evolution)
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Example of a DQT 0.5 B B T A BiasTestActionDecision 0.2 Genetic bias YES Boolean choice Legend VISUAL: FRONT FOOD REACHABLE T NOYES TURN LEFT MOVETURN RIGHT A 0.60.2 PICKUP 1.0 A BAG: FOOD T YESNO TURN LEFT MOVETURN RIGHT A 0.60.2 EAT 1.0 A 0.5
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Interaction evolution & individual learning Bias node with n children each with bias b i Bias ≠ probability Bias b i is learned, changing (name: learned bias) Genetic bias g i is inherited, part of genome, constant Actual probability of choosing child x: p(b,g) = b + (1 - b) ∙ g Learned and inherited behaviour are linked through formula
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DQT nodes & parameters cont’d Test node language: native concepts + emerging concepts Native: see_agent, see_mother, see_food, have_food, see_mate, … New concepts can emerge by categorisation (discrimination game)
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Learning: the heart of the emergence engine Evolutionary learning: not within an agent (not during lifetime), over generations by variation + selection Individual learning: within one agent, during lifetime by reinforcement learning Social learning: during lifetime, in interacting agents by sending/receiving + adopting knowledge pieces
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Types of learning: properties Evolutionary learning: Agent does not create new knowledge during lifetime Basic DQTree + genetic biases are inheritable “knowledge creator” = crossover and mutation Individual learning: Agent does create new knowledge during lifetime DQTree + learned biases are modified “knowledge creator” = reinforcement learning (driven by rewards) Individually learnt knowledge dies with its host agent Social learning: Agent imports knowledge already created elsewhere (new? not new?) Adoption of imported knowledge ≈ crossover Importing knowledge pieces can save effort for recipient can create novel combinations Exporting knowledge helps its preservation after death of host
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Present status of types of learning Evolutionary learning: Demonstrated in 2 NT scenarios Autonomous selection/reproduction causes problems with population stability (im/explosion) Individual learning: code, but never demonstrated in NT scenarios Social learning: Under construction/design based on the “telepathy” approach Communication protocols + adoption mechanisms needed
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Evolution: variation operators Operators for DQT: Crossover = subtree swap Mutation = Substitute subtree with random sub-tree Change concepts in test nodes Change bias on an edge Operators for attitude genes: Crossover = full arithmetic xover Mutation = Add Gaussian noise Replace with random value
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Evolution: selection operators Mate selection: Mate action chosen by DQT Propose – accept proposal Adulthood OK Survivor selection: Dead if too old ( ≥ 80 years) Dead if zero energy
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Experiment: Simple world Setup: Environment World size: 200 x 200 grid cells Agents and food (no tokens, roads, etc). Both are variable in number. Initial distribution of agents (500): in upper left corner Initial distribution of food (10000): 5000 in upper left and lower right corner.
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Experiment: Simple world Setup: Agents Native knowledge (concepts and DQT sub trees) Navigating (random walk) Eating (identify, pickup and eat plants) Mating (identify mates, propose/agree) Random DQT-tree branches Differs per agent Based on the “pool” of native concepts
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Experiment: Simple world Simulation continued for 3 months real time to test stability
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Experiment: Poisonous Food Setup: Environment Two types of food: poisonous (decreases energy) and edible (increases energy) World size: 200 x 200 grid cells Agents and food (no tokens, roads, etc). Both are variable in number. Initial distribution of agents (500): uniform random over the grid space. Initial distribution of food (10000): 5000 of each type of food uniform random over the same grid space as the agents.
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Experiment: Poisonous Food Setup: Agent Native knowledge Identical to simple world experiment Additional native knowledge Can distinguish poisonous from edible plants Relation with eating/picking up is not present No random DQT-tree branches
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Experiment: Poisonous Food Measures Population size Welfare (energy) Number of poisonous and edible plants Complexity of controller (nr. of nodes) Age
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Experiment: Poisonous Food Demo
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Experiment: Poisonous Food Results
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